Tube containers, such as dispensing tubes, are used for storing and dispensing a wide range of products. These include adhesives, lubricants, lotions, medicants, shampoos, hair dressings, and various oral care products, like toothpaste. A problem with such products is that ingredients such as flavors and fragrances may be absorbed, adsorbed, or otherwise degraded by the tube materials or permeate through the tube materials. Some package materials absorb/adsorb flavor and fragrance components in an undesirable manner that may depend on the particular flavor and fragrance molecules. Also, different flavor and fragrance molecules permeate through the package materials at different rates and the taste and/or olfactory properties of the product are changed, often in an unwanted way. One solution for minimizing flavor loss is to modify the tube structure by adding a barrier layer or barrier material to reduce or to eliminate the permeation and the absorption or adsorption by the tube structure of such ingredients. Conventionally, a barrier layer is selected based on its flavor and/or fragrance barrier properties
The shoulder and nozzle of a tube are relatively thick compared to the remainder of a tube in order to maintain the mechanical strength of the tube. Further, in order to have good adhesion or connection of the tube body to the shoulder, and for cost considerations, polyolefins are usually used as the material for the tube shoulder. Because of these properties, the tube shoulder portion of the tubes may poses additional problems with respect to flavor compound loss, because the greater the thickness of the polymers, the greater the absorption. The greater thickness of a tube shoulder leads to an unacceptable level of flavor compound absorption. Additionally, polyolefins do not function as adequate barriers for flavor molecules because flavor molecules can permeate easily through the polyolefins.
Attempts to solve this problem have been made with respect to flavor retention. For example, an insert made of a material that has a high barrier property for the flavor components, such as polyethylene terephthalate (PET), has been used. This insert can be formed by any of several techniques, such as an interference fit into the top part of the tube, or as a film layer onto the inner surface of the tube. However, the use of inserts requires additional manufacturing steps and increases the material cost. In other prior art, a barrier layer (e.g., an ethylene vinyl alcohol—EVOH—or nylon layer) that is co-injection molded in between the shoulder material, high-density polyethylene (HDPE). In these cases, PET is difficult to co-injection mold with PE due to their very different processing temperatures, and while EVOH/nylon can be co-injection molded, they are moisture sensitive and are therefore not co-injected as an inner layer, but are instead formed as a layer buried in PE. However, this involves using a more expensive injection molding machine as well as a more costly injection mold via a complicated injection molding process with a higher molding cycle time, both of which add costs.
It is desirable to provide dispensing tubes that provide performance equal to or better than existing tubes, but which minimize these drawbacks, which reduce the quality of the product in the tube, and which reduce manufacturing costs and operational steps for producing the tube.